if you turn off the render gui everything is fine.

Enabled gui turned off
Enabled gui on (very fast flickering(you can see what's in the slots but the flickering is annoying))

can confirm, the little bar on the left of hotbar from inventorio flickers when having exordium render gui setting enabled

Then they are not compatible with each other. Just remove Exordium.

Fixed by not having other mods being part of Exordium's buffering.